Which factor is essential for the selection of an extraction solvent?

The selection of an extraction solvent is critically dependent on the solvent's solubility with the target compounds. This factor ensures that the desired substances are effectively dissolved in the solvent, facilitating their separation from other components in the mixture. When the solvent has high solubility for the target compounds, it enhances the efficiency of the extraction process, allowing for maximum recovery of the desired materials.

While factors like evaporation rate, cost, and characteristics such as color may be relevant in certain contexts, they do not directly influence the fundamental effectiveness of extracting the target compounds. The primary goal in solvent selection remains the ability to solvate or dissolve the compounds of interest properly, which is why solubility is a decisive criterion in the process.